When my coach calls me through the Vida app, my tablet rings while at the same time my phone starts to ring.
In this case, you are most likely logged into 2 different devices at the same time. This is not suggested, because the call will send to both locations. This will create errors on your side.
This is similar to having your iCloud account signed into multiple devices. If you receive 1 call, it will direct the call to everything that iCloud account is signed into.
Please only be logged into 1 device at a time.